Valve for sequential operation of hydraulic motors



pr 1952 c. B. LIVERS ET AL 2,593,039

VALVE FOR SEQUENTIAL OPERATION OF HYDRAULIC MOTORS Filed July 26, 1949 2 /7 Q INVENTORS I c. B. LIVERS AND A.- A. MEDDOCK ATTORNEY Patented Apr. 1 5, 1952 VA-INETOE SEQUENTIAL OPERATION- OF H HYDRAULIC MGTORS? Garlos. B. Livers North Hollywood; and Al vin. A1.

Meaawmvmmys, CahfZ assignors; to. Ben ix Ayiation; Corporation, South Rena-1nd; a cor porationnfllelaware Application July 26, 1949; Serial;No;.-1i06;934

(c1; err- 97) This invention.v relatesto hydraulic power. systemsin whicha'pai'r ofm'otor cylinders actuated from a commonsource orpressure, fiuid' are, to. be operated in sequence.

Anrobjectof the invention is toprovide a" simplefan'd. practicalvalve forautomati'cally deliveringprjessure'flui'd to onejmotor'until'it' has moved through its stroke): and thereafter switching, the fluid to a second'm'otor'to moveit.

Another object is to provide a; sequence valve for reversible motorsthat: actuates the motors always in' the same sequenceirrespective of the direction of movement;

Another, object" is" to'. provide asequence valve which, although depending i upon a rise in line pressure to switch from: the first to the'second motor, is capable of applying the' nnrime pressuretothe'second'motor:

Other more specific objects-and features of the inventionwill" become apparent from the description to follow: a

Briefly the invention resides ina valve arrangement com rising; in partj a conventional control valve of the 4-waytype which: ina neutralposi-tion' bypasses-theactuating pressure fluid directly to exhaust; in one end position closes the bypass to exhaustand directs the pressure fiiiid'-'toone end of each of the two motors while connecting the other endsof" those motors to exhaust; and the other eh-dpositioncuts oh the bypass of pressure fluid to exhaust while connecting the pressure fiuid' to theother-ends of the motors in parallel" and connectingtheir firstends to exhaust. Such control valves are old and, without any" additional control means; the motor having the lesser load would respond to the pressure fluid and move through its strokei, after which the motor having the greater load would move through its; stroke. The invention includes additional automatic valve means for confining; the fluid flow to a selected one of the motorsuntil it has completed its-stroke irrespective to the relative loads onthe two motors; This-additionalvalve' means includes: a spring-closed va -Ive in each of the ducts leadingto the motor thatisto beactuated las't; with pressure res'pom sive means foropening} these, valves" only afterthe pressure in the==system has risento'a predetermined value; such predetermined pressure being so chosen that it is higher than the pressure required to move th'e first motor under ma-ximum load conditions thereof. I The spring-closed valves are- SQ-(iiSQOSGCP as to b'eoperi'eddirectly in response tofiui'd pressure directed toward the motor cylinder: but these va-lves have opposite 2-1 pressure faces. exposed; to atmosphere, so, that they remain-open so long as the pressure in the ducts is suili'c'iehtv to; overcome the spring, thereby permitting; thefull press'ur'eof the. fluid to be effective. on the motor. In' operation, only one of the valv'es;..thfe one the inlet duct to the motor; is; opened directly by the fluid pressure thereon. The springfkclosed valve in theexhaust d'uct' from thecyli'nder is not affected by pressure in.the duct. on the motor side thereof but, in; accordance withthe'invention, such'valveis opened by an, auxiliary piston; that is exposed. on its frohtifaceto the, full ihletrpressure, and on' its opposite thee. to; exhaust pressure: Therefore, when the, first. more: hasicompleted, its, stroke and me, fluid pressure rises, to the? predetermined value, the valves in both ducts. leading to the secondmifotor are opened by such pressure, and

the'second motor is moved through its stroke. The automatic valve arrangement is symmetrical with'respect to'thetwo ductsleadihgf toithe motor so that? it is reversible" and functions equally well for movement ofth'e'second motor in Both directions; However; regardless of the direction of movement, the firsti'nolto'ralways: moves first, and the second motor moves'last;

A full understanding of the" invention maybe had'from thefollowing detailed description which refers to" the? drawing? motor 1" and; asecondiniotor 2i The motor 1 comprises a cylinder 3" having a" piston 4'" therein and having ports- 5 and (t-a't opposite-end's for the entry anwemiausr ofac't'uati'ng" fluid. The

second motor 2 compfise'sf a' cylinder T having a piston 8" therein and havingoports 9" and I'll at opposite" ends thereof for the entry and discharge 7 Flow-tennis wanemm the m tor; and 2 is cori'trolled by the valve assembly-11* that' ris not" necessary that" it be' adjacent or attached to the motor. This valve assembly II includes a manually operable control valve I2 and a pair of spring-closed pressure actuated valves I3 and I4 respectively. The control valve piston I2 is shown in mid position in Fig. 1, in which it directs fluid from a supply port I5 through an annular recess I6 around a land I201. on the valve piston and out through an exhaust port [1, so that no pressure is developed in the system. The inlet port I5 is permanently connected to a duct I9 which applies the inlet pressure to one end of a pair of valve actuating pistons and 2I respectively, and also applies the inlet pressure to a port 22 displaced from the port I 5 and cooperating with another portion of the control valve I2.

The control valve also has juxtaposed ports 23 and 24. Port 23 is connected to a duct 25 leading to the port 6 of the first motor I, and port 24 communicates with a duct 26 leading to the port 9 of the second motor 2. The control valve has another pair of juxtaposedports 21 and 28 respectively which are connected by ducts 29 and 30 respectively to the port 5 of the first motor I and the port ID of the second motor 2. When the valve [2 is in neutral position, the ports 23 and 24 are closed by a land I2b thereon and the ports 21 and 28 are closed by a land I2c thereon.

Opposite ends of the cylinder 32 in which the control valve I2 reciprocates are at all times connected to the exhaust port H by a passage I2d in the valve I2, the right end of which passage communicates withthe right end of the cylinder 32, the left end of which communicates through a port I2e with the left end of the cylinder, and a port I2 of which communicates with the mid portion of the cylinder where the port I! is located.

Referring now to Fig. 2, in which the control valve I2 has been moved to the left, it will be observed that the land I2a has cut off direct .fiow of fluid (from the inlet port I5 to the exhaust port I1, and has connected the inlet port to the ports 23 and 24. No flow of fluid occurs through port 24 at this time because the spring-closed valve I3 is closed. Therefore all fluid flows through the port 23 and duct 25 to the lower end of motor I, moving it upward, it being shown in about mid stroke position in Fig. 2.

It is to be assumed that the stiffness of the spring I3a on the spring-closed valve I3 is such that it can only be overcome by a pressure applied against the right end of the valve of a predetermined magnitude greater than the pressure required to move the piston of the first motor I under maximum load condition thereof. Hence this valve I3 cannot open until the first motor I has completed its movement, as shown in Fig. 3. The pressure applied through the port 24 to the lower end of duct 26 then rises, and, when it reaches the predetermined value, it overcomes the spring I3a and opens the valve I3, whereupon fluid can flow through the duct 26 into the left end of the second motor 2. ton 3 of the second motor cannot. move in response to pressure fluid in the left end of the motor unless the valve I4 is opened to permit exhaust of fluid from the right end of the motor. Such opening of the valve I4 is efiected simultaneously with or slightly after the opening of the valve I3, by the piston 2|, the left end of which is at all times exposed to the inlet pressure in duct I9, whereas, with the control valve I2 in the position shown in Fig. 3, the lower end Of course the pis- 4 of duct 30 is connected by port 28, the passage I2d and the port I2 with the exhaust port I'I. Although the pistons 29 and 2| are approximately the same diameter as the seats against which the valves I3 and I4 close, they are preferably slightly smaller than the seats, to insure that actuating pressure fluid will be applied to one end of the second motor 2 before the other end is connected to exhaust.

It will be noted that each of the valves I3 and I4'extends through the valve casing to the exterior thereof so that its outer end is exposed to atmospheric pressure. Furthermore the shank portion I3b of valve I3 and I4!) of valve M are of substantially the same diameter as the seats against which the valves close, so that when the valves are closed, as shown in Figs. 1 and 2, pressure in the upper ends of the ducts 26 and 39 respectively are ineffective to hold the valves closed. These valves I3 and I4 are therefore balanced and non-responsive to pressure in the upper ends of the ducts 26 and 30, but are responsive to pressure in the lower ends of those ducts.

It will be noted that in Figs. 2 and 3 both ends of the piston 20 are exposed to the inlet fluid pressure which is applied both to the lower end of the duct 26 and the duct I9, so that the pressures are balanced on the piston and it has no effect on the operation of the valve I3.

Because of the fact that the operation of the valves I3 and I4 is independent of the pressure in the upper ends of the ducts 26 and 30, these valves, when once opened in response to an inlet pressure exceeding the" predetermined value, remain open so long as this pressure is maintained, and the full inlet pressure is effective on the second motor 2. Such would not be the case if the outer end of the valve I3v were exposed to the pressure of fluid in the upper end of the duct 26 instead of to the atmospheric pressure.

When the piston 8 of the second motor 2 has completed its movement to the right, and the control valve I2 is restored to the neutral position shown in Fig. 1, both the first and second motors will be locked into the positions into which they were last moved by closure of the ports 23 and 24 by the valve land I21), and closure of the ports 21 and 28 by the valve land I2c.

If the control valve I2 is moved into its right end position, the valve land I2a is carried beyond the annular groove I6 to block direct flow from the port I5 to the exhaust port IT, and pressure fluid is then delivered from port I5 through the duct I9 to the ports 2'! and 29, so that pressure fluid is applied through the duct 29 to the upper end of the first motor, and to the lower end of the duct 30, which is initially closed by the valve I4. At the same time, the ports 23 and 24 are connected through the'port I 2c, the passage IM and the port I2 f to the exhaust port I'I, so that the firstmotor moves downward. When it has completed its movement, the inlet pressure will rise to the predetermined value, causing the valve I4 to be opened directly by the pressure thereagainst, and causing the valve I3 to be opened by the piston 20 so that the second motor is then moved from right to left.

Although for the purpose of explaining the invention one specific embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and we do not desire to be limited to the exact details shown and described.

We claim;

A hydraulic valve for sequentially controlling the flow of fluid to and from first and second reversible motors comprising: a valve body defining a valve cylinder having a first pair of longitudinally displaced motor port-s adapted to be connected to said first motor, a second pair of motor ports respectively juxtaposed to said first pair of ports, and pressure and exhaust ports longitudinally displaced from each other and from said motor ports; a valve piston re- I ciprccable in said cylinder from a neutral posipiston into one end position connects one of the ports of each pair of motor ports to said pres.- sure port, and the other port of each pair to said exhaust port, and vice versa in response to movement of said piston into the other end position; said body defining a pair of motor passages extending from said second pair of,-

motor ports for connecting them to said second '6 motor and defining a-pair of auxiliary cylinders associated with said respective motor passages; each auxiliary cylinder extending from and communicating its associated motor passage with said pressure port; a spring-closed valve in each motor passage movable into open position in response to predetermined pressure in said passage; and a pressure-responsive piston in each auxiliary cylinder and movable therein to abut against and open the spring-closed valve in the associated motor passage in response to pressure in said pressure port exceeding the pressure in said associated motor passage by substantially said predetermined pressure.

CARLOS B. LIVERS. ALVIN A. MEDDOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,677,860 Ferris July 17, 1928 1,823,426 Ferris Sept. 15, 1931 1,955,154 Temple Apr. 17, 1934 1,994,974 Wiedmann Mar. 19, 1935 2,154,038 Evrell Apr. 11, 1939 2,301,028 Esch Nov. 3, 1942 2,354,860 Hartsock et al. Aug. 1, 1944 

